Polarized America: The Dance of Ideology and Unequal Riches by Nolan McCarty, Keith T. Poole, and Howard Rosenthal. Cambridge, MA: The MIT Press. 2006. ISBN-10:0 262 13464 0; ISBN-13:978 0 262 13464 4, $35.00. 252 pages.
As the punditocracy has frequently observed, and gleefully hyped at times, politics has become more partisan over the last three decades, in particular, since the disputed Presidential election of 2000. Gone are the halcyon days when Republicans and Democrats would square off over important policy questions in the halls of Congress, and later meet at their favorite watering holes to quaff brandies and smoke cigars. The electorate as well seems hopelessly divided into a broad swath of "red states" across the Southern and Western United States, a few "blue states" clustered in the Northeast and along the "left coast," leaving only a few hotly contested "purple" states to receive all the attention once every four years.
Now three respected political scientists have offered a compelling thesis to explain these heightened political divisions in the United States, and have plumbed polling and voting data as well as income and demographic statistics to corroborate their thesis. Nolan McCarty, Keith Poole, and Howard Rosenthal, in their recent book, Polarized America: The Dance of Ideology and Unequal Riches, argue that the increased political polarization is related to the increased economic and social divisions in the United States over this same period, but in a complex "cause and effect" relationship. Indeed, they describe the relationship as a "dance" whereby those at the top of the income pyramid have used their economic clout to support strongly ideological Republican politicians, who in turn have shaped tax policies favorable to more affluent Americans during the Reagan/Bush 1/Bush II eras, or blocked significant changes to the status quo during the Carter/Clinton eras (p. 3).
To measure political polarization, the authors make use of a scaling technique to analyze roll call votes by the members of Congress over the past 120 years to rate the changes in their partisanship. Their evidence documents the strong trend toward political polarization after 1970, specifically, a strong correlation between the economic and demographic characteristics of Congressional districts and increased political polarization. As they state, "family income, a southern location, and college attendance are correlated with more conservative scores...